Würzburg Radar
The low-
UHFUHF band
WürzburgWürzburg radar was the primary ground-based gun
laying radar for the
LuftwaffeLuftwaffe and the Wehrmacht Heer (German Army)
during World War II. Initial development took place before the war and
the apparatus entered service in 1940. Eventually over 4,000
Würzburgs of various models were produced. It took its name from the
city of Würzburg.Contents1 Development
2 Operational models
3 Post-War Use in Astronomy
4 See also
5 Notes
6 References
7 External linksDevelopment[edit]
In January 1934,
TelefunkenTelefunken met with German radar researchers, notably
Dr.
Rudolf Kühnhold of the Communications Research Institute of the
KriegsmarineKriegsmarine and Dr. Hans Hollmann, an expert in microwaves, who
informed them of their work on an early warning radar. Telefunken's
director of research, Dr
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Oscilloscope
An oscilloscope, previously called an oscillograph,[1][2] and
informally known as a scope or o-scope, CRO (for cathode-ray
oscilloscope), or DSO (for the more modern digital storage
oscilloscope), is a type of electronic test instrument that allows
observation of varying signal voltages, usually as a two-dimensional
plot of one or more signals as a function of time. Other signals (such
as sound or vibration) can be converted to voltages and displayed.
Oscilloscopes are used to observe the change of an electrical signal
over time, such that voltage and time describe a shape which is
continuously graphed against a calibrated scale. The observed waveform
can be analyzed for such properties as amplitude, frequency, rise
time, time interval, distortion and others. Modern digital instruments
may calculate and display these properties directly
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Searchlight
A searchlight (or spotlight) is an apparatus that combines an
extremely luminous source (traditionally a carbon arc lamp) with a
mirrored parabolic reflector to project a powerful beam of light of
approximately parallel rays in a particular direction, usually
constructed so that it can be swiveled about.Contents1 Military use1.1 First World War
1.2 Second World War2 Non-military use
3 See also
4 References
5 Notes
6 External linksMilitary use[edit]Russian troops use a searchlight against a Japanese night attack
during the Russo-Japanese War, 1904Military helicopter with searchlightThe first use of searchlights using carbon arc technology occurred
during the Siege of Paris during the Franco-Prussian War.[1] The Royal
Navy used searchlights in 1882 to prevent Egyptian forces from
staffing artillery batteries at Alexandria
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Infra-redInfraredInfrared radiation (IR) is electromagnetic radiation (EMR) with longer
wavelengths than those of visible light, and is therefore generally
invisible to the human eye (although IR at wavelengths up to 1050 nm
from specially pulsed lasers can be seen by humans under certain
conditions [1][2][3][4]). It is sometimes called infrared light. IR
wavelengths extend from the nominal red edge of the visible spectrum
at 700 nanometers (frequency 430 THz), to 1 millimeter
(300 GHz)[5] Most of the thermal radiation emitted by objects
near room temperature is infrared
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Lobe SwitchingLobe switchingLobe switching is a method used on early radar sets to improve
tracking accuracy. It used two slightly separated antenna elements to
send the beam slightly to either side of the midline of the antenna,
switching between the two to find which one gave the stronger return,
thereby indicating which direction the antenna should be moved in
order to point directly at the target. The concept was used only
briefly, and was almost completely replaced by conical scanning
systems by the end of World War II. The concept is also known as
sequential lobing, although this terminology appears to be rare, and
the associated output was sometimes known as a split display.
Description[edit]
Early radar antennas generally consisted of a number of small dipole
antennas in front of a passive reflector. The dipoles were placed in
order to have them constructively interfere in front of the antenna,
thereby "aiming" the signal in that direction
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SCR-268 Radar
The SCR-268 (for
Signal Corps RadioSignal Corps Radio no. 268) was the US Army's first
radar system. It was developed to provide accurate aiming information
and used in gun laying systems and directing searchlights against
aircraft.
The system was already considered out of date by the end of World War
II, having been replaced by the much smaller and more accurate SCR-584
microwave-based system.Three soldiers of the United States Army operate a radar used by the
90th Coast Artillery (Antiaircraft, Semimobile, Colored) in CasablancaContents1 Development
2 Description
3 Surviving examples
4 See also
5 Notes
6 References
7 External linksDevelopment[edit]
The Signal Corps had been experimenting with some radar concepts as
early at the late 1920s, under the direction of Colonel William R.
Blair, director of the
Signal Corps Laboratories at Fort Monmouth, New
Jersey
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Whisk
A whisk is a cooking utensil which can be used to blend ingredients
smooth or to incorporate air into a mixture, in a process known as
whisking or whipping. Most whisks consist of a long, narrow handle
with a series of wire loops joined at the end. The wires are usually
metal, but some are plastic for use with nonstick cookware. Whisks are
also made from bamboo.
Whisks are commonly used to whip egg whites into a firm foam to make
meringue, or to whip cream into whipped cream.
Whisks have differently-shaped loops depending on their intended
functions:Contents1 History
2 Types
3 Mechanisms
4 See also
5 ReferencesHistory[edit]
Bundles of twigs, typically apple, have long been used as whisks;
often the wood used would lend a certain fragrance to the dish. An
18th century
ShakerShaker recipe calls to “Cut a handful of peach twigs
which are filled with sap at this season of the year. Clip the ends
and bruise them and beat the cake batter with them
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V-2 Rocket
maximum:5,760 km/h (3,580 mph)
at impact: 2,880 km/h (1,790 mph)Guidance
systemGyroscopes to determine direction
Müller-type pendulous gyroscopic accelerometer for engine cutoff on
most production rockets[2][3]:225Launch
platformMobile (Meillerwagen)The V-2 (German: Vergeltungswaffe 2, "Retribution Weapon 2"),
technical name Aggregat 4 (A4), was the world's first long-range[4]
guided ballistic missile. The missile, powered by a liquid-propellant
rocket engine, was developed during the
Second World WarSecond World War in Germany as
a "vengeance weapon", assigned to attack Allied cities as retaliation
for the Allied bombings against German cities
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Klystron
A klystron is a specialized linear-beam vacuum tube, invented in 1937
by American electrical engineers Russell and Sigurd Varian,[1] which
is used as an amplifier for high radio frequencies, from UHF up into
the microwave range. Low-power klystrons are used as oscillators in
terrestrial microwave relay communications links, while high-power
klystrons are used as output tubes in UHF television transmitters,
satellite communication, and radar transmitters, and to generate the
drive power for modern particle accelerators.
In a klystron, an electron beam interacts with radio waves as it
passes through resonant cavities, metal boxes along the length of a
tube.[2] The electron beam first passes through a cavity to which the
input signal is applied. The energy of the electron beam amplifies the
signal, and the amplified signal is taken from a cavity at the other
end of the tube
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Radio AstronomyRadio astronomyRadio astronomy is a subfield of astronomy that studies celestial
objects at radio frequencies. The first detection of radio waves from
an astronomical object was in 1932, when
Karl JanskyKarl Jansky at Bell Telephone
Laboratories observed radiation coming from the Milky Way. Subsequent
observations have identified a number of different sources of radio
emission. These include stars and galaxies, as well as entirely new
classes of objects, such as radio galaxies, quasars, pulsars, and
masers. The discovery of the cosmic microwave background radiation,
regarded as evidence for the
Big BangBig Bang theory, was made through radio
astronomy.
Radio astronomyRadio astronomy is conducted using large radio antennas referred to as
radio telescopes, that are either used singularly, or with multiple
linked telescopes utilizing the techniques of radio interferometry and
aperture synthesis
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Hydrogen Line
The hydrogen line, 21-centimeter line or H I line[1] refers to
the electromagnetic radiation spectral line that is created by a
change in the energy state of neutral hydrogen atoms. This
electromagnetic radiation is at the precise frequency of
7009142040575176670♠1420405751.7667±0.0009 Hz,[2] which is
equivalent to the vacuum wavelength of
6999211061140541999♠21.1061140542 cm in free space. This
wavelength falls within the microwave radio region of the
electromagnetic spectrum, and it is observed frequently in radio
astronomy, since those radio waves can penetrate the large clouds of
interstellar cosmic dust that are opaque to visible light.
The microwaves of the hydrogen line come from the atomic transition of
an electron between the two hyperfine levels of the hydrogen 1s ground
state that have an energy difference of ~
7000587433000000000♠5.87433 µeV.[3] It is called the spin-flip
transition
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